What it means
The idea belongs to Keynesian economics, named after the economist John Maynard Keynes, who argued that governments should support demand when private spending collapses. When businesses and households cut back at the same time, a downturn can feed on itself, so the government steps in to break the cycle.
Typical tools include spending on roads, schools and housing, temporary tax reductions, grants to businesses and payments to households. Construction projects are popular because they employ people quickly and create orders for suppliers.
The theory rests on the multiplier effect. Money spent by the government becomes income for workers and firms, who spend part of it again, creating income for others, so the final boost to the economy is larger than the first injection.
In practice the effect is smaller than the textbook model suggests. Some of the extra income is saved, some is taxed and some is spent on imports, and all of these leak out of the loop and reduce the size of the boost.
The approach has real risks. Stimulus is usually financed by borrowing, which raises government debt, and it can push up interest rates or inflation if the economy is already close to full capacity.
Delays between deciding on a project and spending the money can also cause the help to arrive after the recovery has begun. For businesses, pump priming creates opportunities and uncertainty.
Suppliers to public projects may see a surge of orders, but the work is temporary, so finance teams need to plan for the point when the stimulus ends.
In practice
Real-world examples.
Example
After a sharp downturn, a government announces $20,000,000,000 for road and rail projects. A civil engineering contractor wins a large contract, hires 300 workers and orders materials from local suppliers. Those workers spend their wages in nearby shops, spreading the benefit wider.
Example
A city offers a temporary sales tax holiday for six months in the hope of encouraging shoppers back into stores. A retail chain's finance director forecasts a jump in sales volume but also builds in a drop afterwards, because some customers will have bought early.
Example
A government pays energy efficiency grants to homeowners. An insulation company sees demand double for a year, so it rents additional vehicles rather than buying them. The finance team keeps its fixed costs flexible because the scheme has an end date.
Formula
Calculation
Spending multiplier = 1 / (1 - marginal propensity to consume)
Total change in output = initial injection x multiplier
Marginal propensity to consume, or MPC, is the share of each extra dollar of income that people spend. Suppose a government injects $500,000,000 into infrastructure and the MPC is 0.75. The multiplier is 1 / (1 - 0.75) = 1 / 0.25 = 4. Total change in output = 500,000,000 x 4 = $2,000,000,000. If taxes and imports reduce the effective MPC to 0.50, the multiplier falls to 1 / 0.50 = 2 and the total boost is only $1,000,000,000.Case study
Seen in the real world.
Valleyfield is an illustrative, fictional region whose main employer closed a large plant, leaving unemployment high and local shops quiet. The regional government allocated $80,000,000 to rebuild a bridge, upgrade a rail link and subsidise training for displaced workers.
A small construction supplier, Ridgeway Aggregates, saw its orders rise by 40% within six months. Its owner was tempted to buy two new trucks, but her accountant pointed out that the contract pipeline would shrink once the projects were finished.
She leased the trucks on a short agreement and used the extra profit to pay down debt. When the projects ended, private investors had started to use the improved transport links and the supplier's orders settled at a level about 15% above the start. The illustrative lesson is that pump priming helps most when businesses treat the surge as temporary.
Watch out
Common mistakes.
- Treating pump priming as permanent spending, when the whole idea is a temporary push that private demand then replaces.
- Using the textbook multiplier at face value, when leakages through saving, taxes and imports can cut the real effect by half or more.
- Ignoring the cost, since the stimulus is usually paid for by borrowing that has to be repaid or serviced later.
Questions
People also ask.
Does pump priming always work?
Not always, because the result depends on the size and timing of the spending and on whether the economy has spare capacity to respond.
What is the difference between pump priming and ongoing government spending?
Pump priming is a temporary injection meant to restart growth, while ongoing spending is a permanent part of the budget.
How does pump priming relate to the multiplier?
The multiplier is the reason it can work, because each dollar spent is re-spent several times as it circulates in the economy.
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